U.S. patent application number 14/785558 was filed with the patent office on 2016-03-24 for nucleated propylene-based polyolefin compositions.
This patent application is currently assigned to Basell Poliolefine Italia S.r.l.. The applicant listed for this patent is BASELL POLIOLEFINE ITALIA S.R.L.. Invention is credited to Tiziana Caputo, Monica Galvan, Andreas Mann, Antonio Mazzucco, Giampaolo Pellegatti.
Application Number | 20160083561 14/785558 |
Document ID | / |
Family ID | 48139802 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160083561 |
Kind Code |
A1 |
Galvan; Monica ; et
al. |
March 24, 2016 |
NUCLEATED PROPYLENE-BASED POLYOLEFIN COMPOSITIONS
Abstract
A polyolefin composition, particularly fit for the production of
extrusion blow molded articles, comprising (a) a propylene-ethylene
copolymer having a content of units deriving from ethylene of 4.0%
by weight or higher, and (b) a nucleating agent and having a
crystallization temperature (Tc) higher than 117.degree. C. can be
obtained by copolymerizing propylene and ethylene in the presence
of a catalyst system obtained by contacting a solid catalyst
component comprising a magnesium halide, a titanium compound having
at least a Ti-halogen bond and at least two electron donor
compounds one of which being present in an amount from 40 to 90% by
mol with respect to the total amount of donors and selected from
succinates and the other selected from 1,3 diethers, an aluminum
hydrocarbyl compound, and optionally an external electron donor
compound.
Inventors: |
Galvan; Monica; (Ferrara,
IT) ; Mann; Andreas; (Ferrara, IT) ; Caputo;
Tiziana; (Ferrara, IT) ; Mazzucco; Antonio;
(Ferrara, IT) ; Pellegatti; Giampaolo; (Ferrara,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BASELL POLIOLEFINE ITALIA S.R.L. |
Milano |
|
IT |
|
|
Assignee: |
Basell Poliolefine Italia
S.r.l.
Milano
IT
|
Family ID: |
48139802 |
Appl. No.: |
14/785558 |
Filed: |
March 12, 2014 |
PCT Filed: |
March 12, 2014 |
PCT NO: |
PCT/EP2014/054869 |
371 Date: |
October 19, 2015 |
Current U.S.
Class: |
524/117 ;
264/540; 526/125.4 |
Current CPC
Class: |
C08L 23/14 20130101;
C08L 23/14 20130101; C08L 23/14 20130101; C08K 5/1575 20130101;
C08F 210/16 20130101; C08K 5/0083 20130101; C08K 5/0083 20130101;
C08K 5/1575 20130101; C08K 5/527 20130101; C08K 5/527 20130101;
C08K 5/098 20130101; C08F 210/06 20130101; C08K 5/098 20130101;
C08F 4/651 20130101; C08L 23/14 20130101 |
International
Class: |
C08K 5/527 20060101
C08K005/527; C08F 210/16 20060101 C08F210/16 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2013 |
EP |
13164134.2 |
Claims
1. A polyolefin composition comprising: (i) a propylene-ethylene
copolymer having a content of units deriving from ethylene of about
4.0% by weight or higher, and (ii) a nucleating agent; wherein the
composition has a crystallization temperature (Tc), measured by
DSC, higher than 117.degree. C.
2. The polyolefin composition according to claim 1, wherein the
nucleating agent is present in the composition in amounts of up to
about 2500 ppm.
3. The polyolefin composition according to claim 1, wherein the
nucleating agent is selected among
3,4-dimethyldibenzylidenesorbitol,
aluminum-hydroxy-bis[2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate],
sodium or lithium
2,2'-methylene-bis(4,6-ditertbutylphenyl)phosphate and
bicyclo[2.2.1]heptane-2,3-dicarboxylic acid, disodium salt
(1R,2R,3R,4S).
4. A process for the preparation of a propylene-ethylene copolymer
comprising the step of copolymerizing propylene and ethylene in the
presence of a catalyst system comprising the product obtained by
contacting the following components: (a) a solid catalyst component
comprising a magnesium halide, a titanium compound having at least
a Ti-halogen bond and at least two electron donor compounds one of
which being present in an amount from 40 to 90% by mol with respect
to the total amount of donors and selected from succinates and the
other being selected from 1,3 diethers, (b) an aluminum hydrocarbyl
compound, and (c) optionally an external electron donor
compound.
5. The process according to claim 4, wherein the succinate is of
formula (I): ##STR00005## wherein the radicals R.sub.1 and R.sub.2,
equal to, or different from, each other are a C.sub.1-C.sub.20
linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or
alkylaryl group, optionally containing heteroatoms; and the
radicals R.sub.3 and R.sub.4 equal to, or different from, each
other, are C.sub.1-C.sub.20 alkyl, C.sub.3-C.sub.20 cycloalkyl,
C.sub.5-C.sub.20 aryl, arylalkyl or alkylaryl group with the
proviso that at least one of them is a branched alkyl; said
compounds being, with respect to the two asymmetric carbon atoms
identified in the structure of formula (I), stereoisomers of the
type (S,R) or (R,S).
6. The process according to claim 4, wherein the 1,3-diether is of
formula (II): ##STR00006## wherein R.sup.I and R.sup.II are the
same or different and are hydrogen or linear or branched
C.sub.1-C.sub.18 hydrocarbon groups which can also form one or more
cyclic structures; R.sup.III groups, equal or different from each
other, are hydrogen or C.sub.1-C.sub.18 hydrocarbon groups;
R.sup.IV groups equal or different from each other, have the same
meaning of R.sup.II except that they cannot be hydrogen; each of
R.sup.I to R.sup.IV groups can contain heteroatoms selected from
halogens, N, O, S and Si.
7. The process according to claim 4, wherein the catalyst component
(a) has an average particle size ranging from about 15 to about 80
.mu.m.
8. The process according to claim 4, wherein the succinate is
present in amount ranging from about 40 to about 90% by mol with
respect to the total amount of internal donors.
9. (canceled)
10. A process for producing extrusion blow molded articles
comprising the use of a polyolefin composition comprising the steps
of: (i) extruding a parison, from a molten polyolefin composition
comprising: (a) a propylene-ethylene copolymer having a content of
units deriving from ethylene of 4.0% by weight or higher, and (b) a
nucleating agent, wherein the composition has a crystallization
temperature (Tc), measured by DSC; and (c) blow molding the
extruded parison to form a blow-molded article.
11. The polyolefin composition of claim 1 formed into a blow-molded
article.
12. The polyolefin composition of claim 1, wherein the
propylene-ethylene copolymer has a content of units deriving from
ethylene ranging from about 4.0% by weight to about 7.0% by
weight.
13. The polyolefin composition of claim 1, wherein the
crystallization temperature (Tc), measured by DSC, higher than
117.5.degree. C.
14. The polyolefin composition of claim 13, wherein the
crystallization temperature (Tc), measured by DSC, higher than
118.degree. C.
15. The polyolefin composition of claim 2, wherein the nucleating
agent is present in the composition in amounts ranging from about
500 ppm to about 2000 ppm.
16. The polyolefin composition of claim 10, wherein the
propylene-ethylene copolymer has a content of units deriving from
ethylene ranging from about 4.0% by weight to about 7.0% by
weight.
17. The polyolefin composition of claim 10, wherein the
crystallization temperature (Tc), measured by DSC, higher than
117.5.degree. C.
18. The polyolefin composition of claim 17, wherein the
crystallization temperature (Tc), measured by DSC, higher than
118.degree. C.
19. The polyolefin composition of claim 10, wherein the nucleating
agent is present in the composition in amounts up to about 2500
ppm.
20. The polyolefin composition of claim 19, wherein the nucleating
agent is present in the composition in amounts ranging from about
500 ppm to about 2000 ppm.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a nucleated propylene
copolymer composition tailored for use in extrusion blow molding.
The invention also relates to manufactured articles, in particular
extrusion blow molded articles, obtainable from said composition
and to processes for the preparation thereof and of the propylene
copolymer composition.
BACKGROUND OF THE INVENTION
[0002] Propylene copolymers have a good balance of
physical-mechanical properties that makes them fit for use in
extrusion processes, in particular to obtain extrusion blow molded
articles. Propylene copolymers commonly used in extrusion processes
are endowed with an acceptable stiffness, good impact properties
especially at low temperatures and good optical properties, i.e.
low haze values. The desired balance of properties in propylene
copolymers suitable for extrusion processes is normally obtained by
carefully dosing the comonomer content of the propylene copolymers.
Increasing the comonomer content brings about an improvement in the
impact resistance of the copolymers while inevitably deteriorating
the stiffness. On the other hand, lowering the comonomer content
results in improved stiffness but the impact resistance is
worsened. The comonomer content variation has also a strong
influence on the melting and crystallization temperature of
propylene copolymers that are lowered by increasing the comonomer
content.
[0003] International application No. WO 2008/012144 discloses
propylene copolymers having a total content of units deriving from
a linear or branched alpha-olefin having 2 to 8 carbon atoms other
than propylene ranging from 4.5 to 6.0% by weight suitable for use
in extrusion blow molding. Those copolymers may be used in
combination with a nucleating agent.
[0004] In extrusion blow molding the productivity is strongly
influenced by the cooling step, therefore it is important for the
polymer to be endowed with high melting and crystallization
temperature.
[0005] It would be desirable to provide propylene-based polymer
compositions that, when used in extrusion blow molding, show
improved productivity while maintaining a good balance of
physical-mechanical properties.
SUMMARY OF THE INVENTION
[0006] Therefore, according to a first object, the present
invention provides a polyolefin composition comprising: [0007] (a)
a propylene-ethylene copolymer having a content of units deriving
from ethylene of 4.0% by weight or higher, preferably ranging from
4.0 to 7.0% by weight, and [0008] (b) a nucleating agent; wherein
the composition has a crystallization temperature (T.sub.c),
measured by DSC, higher than 117.degree. C., preferably higher than
117.5.degree. C., more preferably higher than 118.degree. C.
DETAILED DESCRIPTION OF THE INVENTION
[0009] The polyolefin composition according to the invention
generally has the following additional features: [0010] melting
temperature (T.sub.m), measured by DSC, of higher than
154.5.degree. C., preferably of 155.degree. C. or higher; [0011]
xylene soluble fraction at 25.degree. C. lower than 18 wt %,
preferably lower than 15 wt %; [0012] melt flow rate (MFR) ranging
from 0.1 to 25 g/10 min, preferably from 0.5 to 5 g/10 min and more
preferably from 1.2 to 2.5 g/10 min.
[0013] The desired MFR can be obtained directly on the "as reactor"
polymers or, particularly for MFR higher than 5 g/10 min, it can be
obtained by visbreaking the "as reactor" polymers according to
known methods.
[0014] The nucleating agent is generally present in the composition
in amounts of up to 2500 ppm, preferably from 500 to 2000 ppm.
[0015] The nucleating agent can be selected among inorganic
additives such as talc, silica or kaolin, salts of monocarboxylic
or polycarboxylic acids, e.g. sodium benzoate or aluminum
tert-butylbenzoate, dibenzylidenesorbitol or its
C1-C8-alkyl-substituted derivatives such as
methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or
dimethyldibenzylidenesorbitol or salts of diesters of phosphoric
acid, e.g. sodium or lithium
2,2'-methylenebis(4,6,-di-tert-butylphenyl)phosphate. Particularly
preferred nucleating agents are 3,4-dimethyldibenzylidenesorbitol;
aluminum-hydroxy-bis[2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate];
sodium or lithium
2,2'-methylene-bis(4,6-ditertbutylphenyl)phosphate and
bicyclo[2.2.1]heptane-2,3-dicarboxylic acid, disodium salt
(1R,2R,3R,4S). The at least one nucleating agent may be added to
the propylene polymer by known methods, such as by melt blending
the at least one nucleating agent and the propylene polymer under
shear condition in a conventional extruder.
[0016] The propylene-ethylene copolymers for use in the composition
of the present invention are obtainable by polymerizing propylene
and ethylene in the presence of specific Ziegler-Natta
catalysts.
[0017] Therefore, according to another object the present invention
provides a process for the preparation of a propylene-ethylene
copolymer comprising the step of copolymerizing propylene and
ethylene in the presence of a catalyst system comprising the
product obtained by contacting the following components:
(a) a solid catalyst component comprising a magnesium halide, a
titanium compound having at least a Ti-halogen bond and at least
two electron donor compounds one of which being present in an
amount from 40 to 90% by mol with respect to the total amount of
donors and selected from succinates and the other being selected
from 1,3 diethers, (b) an aluminum hydrocarbyl compound, and (c)
optionally an external electron donor compound.
[0018] In the solid catalyst component (a) the succinate is
preferably selected from succinates of formula (I):
##STR00001##
in which the radicals R.sub.1 and R.sub.2, equal to, or different
from, each other are a C.sub.1-C.sub.20 linear or branched alkyl,
alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally
containing heteroatoms; and the radicals R.sub.3 and R.sub.4 equal
to, or different from, each other, are C.sub.1-C.sub.20 alkyl,
C.sub.3-C.sub.20 cycloalkyl, C.sub.5-C.sub.20 aryl, arylalkyl or
alkylaryl group with the proviso that at least one of them is a
branched alkyl; said compounds being, with respect to the two
asymmetric carbon atoms identified in the structure of formula (I),
stereoisomers of the type (S,R) or (R,S) R.sub.1 and R.sub.2 are
preferably C.sub.1-C.sub.8 alkyl, cycloalkyl, aryl, arylalkyl and
alkylaryl groups. Particularly preferred are the compounds in which
R.sup.1 and R.sup.2 are selected from primary alkyls and in
particular branched primary alkyls. Examples of suitable R.sup.1
and R.sup.2 groups are methyl, ethyl, n-propyl, n-butyl, isobutyl,
neopentyl, 2-ethylhexyl. Particularly preferred are ethyl,
isobutyl, and neopentyl.
[0019] Particularly preferred are the compounds in which the R3
and/or R4 radicals are secondary alkyls like isopropyl, sec-butyl,
2-pentyl, 3-pentyl or cycloakyls like cyclohexyl, cyclopentyl,
cyclohexylmethyl.
[0020] Examples of the above-mentioned compounds are the (S,R)(S,R)
forms pure or in mixture, optionally in racemic form, of diethyl
2,3-bis(trimethylsilyl)succinate, diethyl
2,3-bis(2-ethylbutyl)succinate, diethyl 2,3-dibenzylsuccinate,
diethyl 2,3-diisopropylsuccinate, diisobutyl
2,3-diisopropylsuccinate, diethyl
2,3-bis(cyclohexylmethyl)succinate, diethyl
2,3-diisobutylsuccinate, diethyl 2,3-dineopentylsuccinate, diethyl
2,3-dicyclopentylsuccinate, diethyl 2,3-dicyclohexylsuccinate.
[0021] Among the 1,3-diethers mentioned above, particularly
preferred are the compounds of formula (II):
##STR00002##
where R.sup.I and R.sup.II are the same or different and are
hydrogen or linear or branched C.sub.1-C.sub.18 hydrocarbon groups
which can also form one or more cyclic structures; R.sup.III
groups, equal or different from each other, are hydrogen or
C.sub.1-C.sub.18 hydrocarbon groups; R.sup.IV groups equal or
different from each other, have the same meaning of R.sup.III
except that they cannot be hydrogen; each of R.sup.I to R.sup.IV
groups can contain heteroatoms selected from halogens, N, O, S and
Si.
[0022] Preferably, R.sup.IV is a 1-6 carbon atom alkyl radical and
more particularly a methyl while the R.sup.III radicals are
preferably hydrogen. Moreover, when R.sup.I is methyl, ethyl,
propyl, or isopropyl, R.sup.II can be ethyl, propyl, isopropyl,
butyl, isobutyl, tert-butyl, isopentyl, 2-ethylhexyl, cyclopentyl,
cyclohexyl, methylcyclohexyl, phenyl or benzyl; when RI is
hydrogen, R.sup.II can be ethyl, butyl, sec-butyl, tert-butyl,
2-ethylhexyl, cyclohexylethyl, diphenylmethyl, p-chlorophenyl,
1-naphthyl, 1-decahydronaphthyl; RI and RII can also be the same
and can be ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl,
neopentyl, phenyl, benzyl, cyclohexyl, cyclopentyl.
[0023] Specific examples of ethers that can be advantageously used
include: 2-(2-ethylhexyl)1,3-dimethoxypropane,
2-isopropyl-1,3-dimethoxypropane, 2-butyl-1,3-dimethoxypropane,
2-sec-butyl-1,3-dimethoxypropane,
2-cyclohexyl-1,3-dimethoxypropane, 2-phenyl-1,3-dimethoxypropane,
2-tert-butyl-1,3-dimethoxypropane, 2-cumyl-1,3-dimethoxypropane,
2-(2-phenylethyl)-1,3-dimethoxypropane,
2-(2-cyclohexylethyl)-1,3-dimethoxypropane,
2-(p-chlorophenyl)-1,3-dimethoxypropane,
2-(diphenylmethyl)-1,3-dimethoxypropane,
2(1-naphthyl)-1,3-dimethoxypropane,
2(p-fluorophenyl)-1,3-dimethoxypropane,
2(1-decahydronaphthyl)-1,3-dimethoxypropane,
2(p-tert-butylphenyl)-1,3-dimethoxypropane,
2,2-dicyclohexyl-1,3-dimethoxypropane,
2,2-diethyl-1,3-dimethoxypropane,
2,2-dipropyl-1,3-dimethoxypropane,
2,2-dibutyl-1,3-dimethoxypropane, 2,2-diethyl-1,3-diethoxypropane,
2,2-dicyclopentyl-1,3-dimethoxypropane,
2,2-dipropyl-1,3-diethoxypropane, 2,2-dibutyl-1,3-diethoxypropane,
2-methyl-2-ethyl-1,3-dimethoxypropane,
2-methyl-2-propyl-1,3-dimethoxypropane,
2-methyl-2-benzyl-1,3-dimethoxypropane,
2-methyl-2-phenyl-1,3-dimethoxypropane,
2-methyl-2-cyclohexyl-1,3-dimethoxypropane,
2-methyl-2-methylcyclohexyl-1,3-dimethoxypropane,
2,2-bis(p-chlorophenyl)-1,3-dimethoxypropane,
2,2-bis(2-phenylethyl)-1,3-dimethoxypropane,
2,2-bis(2-cyclohexylethyl)-1,3-dimethoxypropane,
2-methyl-2-isobutyl-1,3-dimethoxypropane,
2-methyl-2-(2-ethylhexyl)-1,3-dimethoxypropane,
2,2-bis(2-ethylhexyl)-1,3-dimethoxypropane,
2,2-bis(p-methylphenyl)-1,3-dimethoxypropane,
2-methyl-2-isopropyl-1,3-dimethoxypropane,
2,2-diisobutyl-1,3-dimethoxypropane,
2,2-diphenyl-1,3-dimethoxypropane,
2,2-dibenzyl-1,3-dimethoxypropane,
2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane,
2,2-bis(cyclohexylmethyl)-1,3-dimethoxypropane,
2,2-diisobutyl-1,3-diethoxypropane,
2,2-diisobutyl-1,3-dibutoxypropane,
2-isobutyl-2-isopropyl-1,3-dimetoxypropane,
2,2-di-sec-butyl-1,3-dimetoxypropane,
2,2-di-tert-butyl-1,3-dimethoxypropane,
2,2-dineopentyl-1,3-dimethoxypropane,
2-iso-propyl-2-isopentyl-1,3-dimethoxypropane,
2-phenyl-2-benzyl-1,3-dimetoxypropane,
2-cyclohexyl-2-cyclohexylmethyl-1,3-dimethoxypropane.
[0024] Furthermore, particularly preferred are the 1,3-diethers of
formula (III):
##STR00003##
where the radicals R.sup.IV have the same meaning explained above
and the radicals R.sup.III and R.sup.V radicals, equal or different
to each other, are selected from the group consisting of hydrogen;
halogens, preferably Cl and F; C.sub.1-C.sub.20 alkyl radicals,
linear or branched; C.sub.3-C.sub.20 cycloalkyl, C.sub.6-C.sub.20
aryl, C.sub.7-C.sub.20 alkaryl and C.sub.7-C.sub.20 aralkyl
radicals and two or more of the R.sup.V radicals can be bonded to
each other to form condensed cyclic structures, saturated or
unsaturated, optionally substituted with R.sup.VI radicals selected
from the group consisting of halogens, preferably Cl and F;
C.sub.1-C.sub.20 alkyl radicals, linear or branched;
C.sub.3-C.sub.20 cycloalkyl, C.sub.6-C.sub.20 aryl,
C.sub.7-C.sub.20 alkaryl and C.sub.7-C.sub.20 aralkyl radicals;
said radicals R.sup.V and R.sup.VI optionally containing one or
more heteroatoms as substitutes for carbon or hydrogen atoms, or
both.
[0025] Preferably, in the 1,3-diethers of formulae (I) and (II) all
the R.sup.III radicals are hydrogen, and all the R.sup.IV radicals
are methyl. Moreover, are particularly preferred the 1,3-diethers
of formula (II) in which two or more of the R.sup.V radicals are
bonded to each other to form one or more condensed cyclic
structures, preferably benzenic, optionally substituted by R.sup.VI
radicals. Specially preferred are the compounds of formula
(IV):
##STR00004##
where the R.sup.VI radicals equal or different are hydrogen;
halogens, preferably Cl and F; C.sub.1-C.sub.20 alkyl radicals,
linear or branched; C.sub.3-C.sub.20 cycloalkyl, C.sub.6-C.sub.20
aryl, C.sub.7-C.sub.20 alkylaryl and C.sub.7-C.sub.20 aralkyl
radicals, optionally containing one or more heteroatoms selected
from the group consisting of N, O, S, P, Si and halogens, in
particular Cl and F, as substitutes for carbon or hydrogen atoms,
or both; the radicals R.sup.III and R.sup.IV are as defined above
for formula (II). Specific examples of compounds comprised in
formulae (II) and (III) are: [0026]
1,1-bis(methoxymethyl)-cyclopentadiene; [0027]
1,1-bis(methoxymethyl)-2,3,4,5-tetramethylcyclopentadiene; [0028]
1,1-bis(methoxymethyl)-2,3,4,5-tetraphenylcyclopentadiene; [0029]
1,1-bis(methoxymethyl)-2,3,4,5-tetrafluorocyclopentadiene; [0030]
1,1-bis(methoxymethyl)-3,4-dicyclopentylcyclopentadiene; [0031]
1,1-bis(methoxymethyl)indene;
1,1-bis(methoxymethyl)-2,3-dimethylindene; [0032]
1,1-bis(methoxymethyl)-4,5,6,7-tetrahydroindene; [0033]
1,1-bis(methoxymethyl)-2,3,6,7-tetrafluoroindene; [0034]
1,1-bis(methoxymethyl)-4,7-dimethylindene; [0035]
1,1-bis(methoxymethyl)-3,6-dimethylindene; [0036]
1,1-bis(methoxymethyl)-4-phenylindene; [0037]
1,1-bis(methoxymethyl)-4-phenyl-2-methylindene; [0038]
1,1-bis(methoxymethyl)-4-cyclohexylindene; [0039]
1,1-bis(methoxymethyl)-7-(3,3,3-trifluoropropyl)indene; [0040]
1,1-bis(methoxymethyl)-7-trimethyisilylindene; [0041]
1,1-bis(methoxymethyl)-7-trifluoromethylindene; [0042]
1,1-bis(methoxymethyl)-4,7-dimethyl-4,5,6,7-tetrahydroindene;
[0043] 1,1-bis(methoxymethyl)-7-methylindene; [0044]
1,1-bis(methoxymethyl)-7-cyclopenthylindene; [0045]
1,1-bis(methoxymethyl)-7-isopropylindene; [0046]
1,1-bis(methoxymethyl)-7-cyclohexylindene; [0047]
1,1-bis(methoxymethyl)-7-tert-butylindene; [0048]
1,1-bis(methoxymethyl)-7-tert-butyl-2-methylindene; [0049]
1,1-bis(methoxymethyl)-7-phenylindene; [0050]
1,1-bis(methoxymethyl)-2-phenylindene; [0051]
1,1-bis(methoxymethyl)-1H-benz[e]indene; [0052]
1,1-bis(methoxymethyl)-1H-2-methylbenz[e]indene; [0053]
9,9-bis(methoxymethyl)fluorene; [0054]
9,9-bis(methoxymethyl)-2,3,6,7-tetramethylfluorene; [0055]
9,9-bis(methoxymethyl)-2,3,4,5,6,7-hexafluorofluorene; [0056]
9,9-bis(methoxymethyl)-2,3-benzofluorene; [0057]
9,9-bis(methoxymethyl)-2,3,6,7-dibenzofluorene; [0058]
9,9-bis(methoxymethyl)-2,7-diisopropylfluorene; [0059]
9,9-bis(methoxymethyl)-1,8-dichlorofluorene; [0060]
9,9-bis(methoxymethyl)-2,7-dicyclopentylfluorene; [0061]
9,9-bis(methoxymethyl)-1,8-difluorofluorene; [0062]
9,9-bis(methoxymethyl)-1,2,3,4-tetrahydrofluorene; [0063]
9,9-bis(methoxymethyl)-1,2,3,4,5,6,7,8-octahydrofluorene; [0064]
9,9-bis(methoxymethyl)-4-tert-butylfluorene.
[0065] As explained above, the catalyst component (a) comprises, in
addition to the above electron donors, a titanium compound having
at least a Ti-halogen bond and a Mg halide. The magnesium halide is
preferably MgCl.sub.2 in active form which is widely known from the
patent literature as a support for Ziegler-Natta catalysts. U.S.
Pat. No. 4,298,718 and U.S. Pat. No. 4,495,338 were the first to
describe the use of these compounds in Ziegler-Natta catalysis. It
is known from these patents that the magnesium dihalides in active
form used as support or co-support in components of catalysts for
the polymerization of olefins are characterized by X-ray spectra in
which the most intense diffraction line that appears in the
spectrum of the non-active halide is diminished in intensity and is
replaced by a halo whose maximum intensity is displaced towards
lower angles relative to that of the more intense line.
[0066] The preferred titanium compounds used in the catalyst
component of the present invention are TiCl.sub.4 and TiCl.sub.3;
furthermore, also Ti-haloalcoholates of formula
Ti(OR).sub.n-yX.sub.y can be used, where n is the valence of
titanium, y is a number between 1 and n-1 X is halogen and R is a
hydrocarbon radical having from 1 to 10 carbon atoms.
[0067] Preferably, the catalyst component (a) has an average
particle size ranging from 15 to 80 .mu.m, more preferably from 20
to 70 .mu.m and even more preferably from 25 to 65 .mu.m. As
explained the succinate is present in an amount ranging from 40 to
90% by weight with respect to the total amount of donors.
Preferably it ranges from 50 to 85% by weight and more preferably
from 65 to 80% by weight. The 1,3-diether preferably constitutes
the remaining amount.
[0068] The alkyl-Al compound (b) is preferably chosen among the
trialkyl aluminum compounds such as for example triethylaluminum,
tri-n-hexylaluminum, tri-n-octylaluminum. It is also possible to
use mixtures of trialkylaluminum's with alkylaluminum halides,
alkylaluminum hydrides or alkylaluminum sesquichlorides such as
AlEt.sub.2Cl and Al.sub.2Et.sub.3Cl.sub.3.
[0069] Preferred external electron-donor compounds include silicon
compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines,
heterocyclic compounds and particularly 2,2,6,6-tetramethyl
piperidine, ketones and the 1,3-diethers. Another class of
preferred external donor compounds is that of silicon compounds of
formula R.sub.a.sup.5R.sub.b.sup.6Si(OR.sup.7).sub.c, where a and b
are integer from 0 to 2, c is an integer from 1 to 3 and the sum
(a+b+c) is 4; R.sup.5, R.sup.6, and R.sup.7, are alkyl, cycloalkyl
or aryl radicals with 1-18 carbon atoms optionally containing
heteroatoms. Particularly preferred are
methylcyclohexyldimethoxysilane, diphenyldimethoxysilane,
methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane,
2-ethylpiperidinyl-2-t-butyldimethoxysilane and
1,1,1,trifluoropropyl-2-ethylpiperidinyl-dimethoxysilane and
1,1,1,trifluoropropyl-metil-dimethoxysilane. The external electron
donor compound is used in such an amount to give a molar ratio
between the organo-aluminum compound and said electron donor
compound of from 5 to 500, preferably from 5 to 400 and more
preferably from 10 to 200.
[0070] The catalyst forming components can be contacted with a
liquid inert hydrocarbon solvent such as, e.g., propane, n-hexane
or n-heptane, at a temperature below about 60.degree. C. and
preferably from about 0 to 30.degree. C. for a time period of from
about 6 seconds to 60 minutes.
[0071] The above catalyst components (a), (b) and optionally (c)
can be fed to a pre-contacting vessel, in amounts such that the
weight ratio (b)/(a) is in the range of 0.1-10 and if the compound
(c) is present, the weight ratio (b)/(c) is weight ratio
corresponding to the molar ratio as defined above. Preferably, the
said components are pre-contacted at a temperature of from 10 to
20.degree. C. for 1-30 minutes. The precontact vessel is generally
a stirred tank reactor. Preferably, the precontacted catalyst is
then fed to a prepolymerization reactor where a prepolymerization
step takes place. The prepolymerization step can be carried out in
a first reactor selected from a loop reactor or a continuously
stirred tank reactor, and is generally carried out in liquid-phase.
The liquid medium comprises liquid alpha-olefin monomer(s),
optionally with the addition of an inert hydrocarbon solvent. Said
hydrocarbon solvent can be either aromatic, such as toluene, or
aliphatic, such as propane, hexane, heptane, isobutane, cyclohexane
and 2,2,4-trimethylpentane. The amount of hydrocarbon solvent, if
any, is lower than 40% by weight with respect to the total amount
of alpha-olefins, preferably lower than 20% by weight. Preferably,
step (i) a is carried out in the absence of inert hydrocarbon
solvents.
[0072] The average residence time in this reactor generally ranges
from 2 to 40 minutes, preferably from 5 to 25 minutes. The
temperature ranges between 10.degree. C. and 50.degree. C.,
preferably between 15.degree. C. and 35.degree. C. Adopting these
conditions allows to obtain a pre-polymerization degree in the
preferred range from 60 to 800 g per gram of solid catalyst
component, preferably from 150 to 500 g per gram of solid catalyst
component. Step (i) a is further characterized by a low
concentration of solid in the slurry, typically in the range from
50 g to 300 g of solid per liter of slurry.
[0073] The slurry containing the catalyst, preferably in
pre-polymerized form, is discharged from the pre-polymerization
reactor and fed to a gas-phase or liquid-phase polymerization
reactor.
[0074] In case of a gas-phase reactor, it generally consists of a
fluidized or stirred, fixed bed reactor or of a reactor comprising
two interconnected polymerization zones one of which, working under
fast fluidization conditions (riser) and the other in which the
polymer flows under the action of gravity (downer). In this latter
case, the reaction mixture in the two zones can suitably be
maintained different by the introduction in the downer of a gas
and/or liquid mixture having a composition different from the gas
mixture present in the riser, as described in International
application No. WO 00/02929.
[0075] The liquid phase process can be either in slurry, solution
or bulk (liquid monomer). This latter technology can be carried out
in various types of reactors such as continuous stirred tank
reactors, loop reactors or plug-flow ones.
[0076] The polymerization is generally carried out at temperature
of from 20 to 120.degree. C., preferably of from 40 to 85.degree.
C. When the polymerization is carried out in gas-phase the
operating pressure is generally between 0.5 and 10 MPa, preferably
between 1 and 5 MPa. In the bulk polymerization the operating
pressure is generally between 1 and 6 MPa preferably between 1.5
and 4 MPa. Hydrogen can be used as a molecular weight
regulator.
[0077] The polyolefin compositions of the present invention have
the additional advantage that the articles produced therefrom do
not contain phthalate residues.
[0078] The polyolefin compositions of the present invention can
also contain additives commonly employed in the art, such as
antioxidants, light stabilizers, heat stabilizers, nucleating
agents, colorants and fillers. Particularly, they can comprise an
inorganic filler agent in an amount ranging from 0.5 to 60 parts by
weight with respect to 100 parts by weight of the said polyolefin
composition. Typical examples of such filler agents are calcium
carbonate, barium sulphate, titanium bioxide and talc. Talc and
calcium carbonate are preferred. A number of filler agents can also
have a nucleating effect, such as talc that is also a nucleating
agent.
[0079] It has been surprisingly found that the polyolefin
compositions of the present invention show improved optical
properties, notably haze, as well as excellent impact properties,
particularly bi-axial impact resistance, making them particularly
suitable for producing extrusion blow molded articles.
[0080] It is therefore a further object of the present invention an
extrusion blow molded article obtained from a polyolefin
composition comprising:
(a) a propylene-ethylene copolymer having a content of units
deriving from ethylene of 4.0% by weight or higher, preferably
ranging from 4.0 to 7.0% by weight, and (b) a nucleating agent;
wherein the composition has a crystallization temperature (Tc),
measured by DSC, higher than 117.degree. C., preferably higher than
117.5.degree. C., more preferably higher than 118.degree. C.
[0081] According to a still further object, the present invention
provides a process for producing extrusion blow molded articles
comprising the steps of: [0082] (i) extruding a hollow cylinder
(parison) from a molten polyolefin composition comprising: [0083]
(a) a propylene-ethylene copolymer having a content of units
deriving from ethylene of 4.0% by weight or higher, preferably
ranging from 4.0 to 7.0% by weight, and [0084] (b) a nucleating
agent, wherein the composition has a crystallization temperature
(Tc), measured by DSC, higher than 117.degree. C., preferably
higher than 117.5.degree. C., more preferably higher than
118.degree. C.; and [0085] (ii) blow molding the extruded parison
to form a blow-molded article.
[0086] The extruded parison in clamped in a mold and, while still
warm enough to be soft and moldable, subjected to significant
internal air pressure and expanded against the mold, then cooled
and ejected. Flash is an inevitable by-product of the extrusion
blow molding process and trim tooling is needed to remove the flash
from the blow molded articles. The cooling step is therefore the
rate limiting factor in the process and the cooling capacity of the
molten material is of the uttermost importance in determining the
minimum cycle time. It has been found that by using the
propylene-based polymer compositions of the invention the cycle
time of extrusion blow molding processes can be significantly
reduced with respect to the same processes wherein a conventional
polypropylene is used.
[0087] The following examples are given to illustrate the present
invention without any limiting purpose.
EXAMPLES
Methods
Molar Ratio of Feed Gases
[0088] Determined by gas-chromatography.
Average Particle Size of the Adduct and Catalysts
[0089] Determined by a method based on the principle of the optical
diffraction of monochromatic laser light with the "Malvern Instr.
2600" apparatus. The average size is given as P50.
Comonomer Content
[0090] The content of comonomers was determined by infrared
spectroscopy by collecting the IR spectrum of the sample vs. an air
background with a Fourier Transform Infrared spectrometer (FTIR).
The instrument data acquisition parameters are: [0091] purge time:
30 seconds minimum [0092] collect time: 3 minutes minimum [0093]
apodization: Happ-Genzel [0094] resolution: 2 cm-1.
[0095] Sample Preparation--Using a hydraulic press, a thick sheet
is obtained by pressing about g 1 of sample between two aluminum
foils. A small portion is cut from this sheet to mold a film.
Recommended film thickness ranges between 0.02 and 0.05 cm (8-20
mils). Pressing temperature is 180.+-.10.degree. C. (356.degree.
F.) and about 10 kg/cm.sup.2 (142.2 PSI) pressure for about one
minute. The pressure is released, the sample removed from the press
and cooled to room temperature.
[0096] The spectrum of pressed film sample is recorded in
absorbance vs. wavenumbers (cm.sup.-1). The following measurements
are used to calculate ethylene and 1-butene content: [0097] Area
(At) of the combination absorption bands between 4482 and 3950
cm.sup.-1 which is used for spectrometric normalization of film
thickness; [0098] Area (AC2) of the absorption band between 750-700
cm.sup.-1 after two proper consecutive spectroscopic subtractions
of an isotactic non-additivated polypropylene spectrum and then of
a reference spectrum of an 1-butene-propylene random copolymer in
the range 800-690 cm.sup.-1; [0099] Height (DC4) of the absorption
band at 769 cm.sup.-1 (maximum value), after two proper consecutive
spectroscopic subtractions of an isotactic non-additivated
polypropylene spectrum and then of a reference spectrum of an
ethylene-propylene random copolymer in the range 800-690
cm.sup.-1.
[0100] In order to calculate the ethylene and 1-butene content,
calibration straights lines for ethylene and 1-butene obtained by
using samples of known amount of ethylene and 1-butene are
needed:
[0101] Calibration for ethylene--A calibration straight line is
obtained by plotting AC2/At versus ethylene molar percent (% C2m).
The slope GC2 is calculated from a linear regression.
[0102] Calibration for 1-butene--A calibration straight line is
obtained by plotting DC4/At versus butene molar percent (% C4m).
The slope GC4 is calculated from a linear regression.
[0103] The spectra of the unknown samples are recorded and then
(At), (AC2) and (DC4) of the unknown sample are calculated. The
ethylene content (% molar fraction C2m) of the sample is calculated
as follows:
% C 2 m = 1 G C 2 A C 2 A t ##EQU00001##
[0104] The 1-butene content (% molar fraction C4m) of the sample is
calculated as follows:
% C 4 m = 1 G C 4 ( A C 4 A t - I C 4 ) ##EQU00002##
[0105] The propylene content (molar fraction C3m) is calculated as
follows:
C3m=100-%C4m-%C2m
[0106] The ethylene, 1-butene contents by weight are calculated as
follows:
% C 2 wt = 100 28 C 2 m ( 56 C 4 m + 42 C 3 m + 28 C 2 m )
##EQU00003## % C 4 wt = 100 56 C 4 m ( 56 C 4 m + 42 C 3 m + 28 C 2
m ) ##EQU00003.2##
Melt Flow Rate (MFR "L")
[0107] Determined according to ISO 1133 (230.degree. C., 2.16
Kg)
Melting Temperature (T.sub.m) and Crystallization Temperature
(T.sub.c)
[0108] Both determined by differential scanning calorimetry (DSC)
according to the ASTM D 3417 method, which is equivalent to the ISO
11357/1 and 3 method.
Xylene Solubles
[0109] Determined as follows: 2.5 g of polymer and 250 ml of xylene
are introduced in a glass flask equipped with a refrigerator and a
magnetic stirrer. The temperature is raised in 30 minutes up to the
boiling point of the solvent. The so obtained clear solution is
then kept under reflux and stirring for further 30 minutes. The
closed flask is then kept in thermostatic water bath at 25.degree.
C. for 30 minutes. The so formed solid is filtered on quick
filtering paper. 100 ml of the filtered liquid is poured in a
previously weighed aluminum container, which is heated on a heating
plate under nitrogen flow, to remove the solvent by evaporation.
The container is then kept on an oven at 80.degree. C. under vacuum
until constant weight is obtained. The weight percentage of polymer
soluble in xylene at room temperature is then calculated.
Ductile Brittle Transition Temperature (DB/TT)
[0110] According to this method, the bi-axial impact resistance is
determined through impact with an automatic, computerized striking
hammer. The circular test specimens are obtained by cutting with
circular hand punch (38 mm diameter) plaques obtained as described
below. The circular test specimens are conditioned for at least 12
hours at 23.degree. C. and 50 RH and then placed in a thermostatic
bath at testing temperature for 1 hour. The force-time curve is
detected during impact of a striking hammer (5.3 kg, hemispheric
punch with a 1/2'' diameter) on a circular specimen resting on a
ring support. The machine used is a CEAST 6758/000 type model no.
2. The DB/TT is the temperature at which 50% of the samples
undergoes fragile break when submitted to the above-mentioned
impact test. The plaques for DB/TT measurements, having dimensions
of 127.times.127.times.1.5 mm are prepared according to the
following method. The injection press is a Negri Bossi.TM. type (NB
90) with a clamping force of 90 tons. The mold is a rectangular
plaque (127 127 1.5 mm). Main process parameters are reported
below: [0111] Back pressure: 20 bar [0112] Injection time: 3 sec
[0113] Maximum Injection pressure: 14 MPa [0114] Hydraulic
injection pressure: 6-3 MPa [0115] First holding hydraulic
pressure: 4.+-.2 MPa [0116] First holding time: 3 sec [0117] Second
holding hydraulic pressure: 3.+-.2 MPa [0118] Second holding time:
7 sec [0119] Cooling time: 20 sec [0120] Mold temperature:
60.degree. C. [0121] Melt temperature 220 to 280.degree. C.
Haze (on 1 mm Plaque)
[0122] According to the present method, 5.times.5 cm specimens are
cut molded plaques of 1 mm thick and the haze value is measured
using a Gardner photometric unit connected to a Hazemeter type
UX-10 or an equivalent instrument having G.E. 1209 light source
with filter "C". Reference samples of known haze are used for
calibrating the instrument. The plaques to be tested are produced
according to the following method. 75.times.75.times.1 mm plaques
are molded with a GBF Plastiniector G235/90 Injection Molding
Machine, 90 tons under the following processing conditions: [0123]
Screw rotation speed: 120 rpm [0124] Back pressure: 10 bar [0125]
Melt temperature: 260.degree. C. [0126] Injection time: 5 sec
[0127] Switch to hold pressure: 50 bar [0128] First stage hold
pressure: 30 bar [0129] Second stage pressure: 20 bar [0130] Hold
pressure profile (1st stage): 5 sec [0131] Hold pressure profile
(2nd stage): 10 sec [0132] Cooling time: 20 sec [0133] Mold water
temperature: 40.degree. C.
Example 1
Preparation of the Solid Catalyst Component
[0134] Into a 500 mL four-necked round flask, purged with nitrogen,
250 mL of TiCl.sub.4 were introduced at 0.degree. C. While
stirring, 10.0 g of microspheroidal MgCl.sub.2.2.1C.sub.2H.sub.5OH
having average particle size of 47 .mu.m (prepared in accordance
with the method described in example 1 of EP728769) and an amount
of diethyl 2,3-diisopropylsuccinate such as to have a Mg/succinate
molar ratio of 15 were added. The temperature was raised to
100.degree. C. and kept at this value for 60 minutes. After that
the stirring was stopped and the liquid was siphoned off. After
siphoning, fresh TiCl.sub.4 and an amount of
9,9-bis(methoxymethyl)fluorene such as to have a Mg/diether molar
ratio of 30 were added. Then the temperature was raised to
110.degree. C. and kept for 30 minutes under stirring. After
sedimentation and siphoning at 85.degree. C., fresh TiCl.sub.4 was
added. Then the temperature was raised to 90.degree. C. for 15 min.
After sedimentation and siphoning at 90.degree. C. the solid was
washed three times with anhydrous hexane (3.times.100 ml) at
60.degree. C. and additional three times with anhydrous hexane
(3.times.100 ml) at 25.degree. C. The obtained solid catalyst
component had a total amount of internal electron donor compounds
of 12.0% by weight with respect to the weight of the solid catalyst
component.
Preparation of the Catalyst System--Precontact
[0135] Before introducing it into the polymerization reactors, the
solid catalyst component described above is contacted with
aluminum-triethyl (TEAL) and with di-cylopentyl-di-methoxy-silane
(DCPMS) under the conditions reported in Table 1.
Prepolymerization
[0136] The catalyst system is then subject to prepolymerization
treatment at 20.degree. C. by maintaining it in suspension in
liquid propylene for a residence time of 9 minutes before
introducing it into the polymerization reactor.
Polymerization
[0137] The polymerization was carried out in gas-phase
polymerization reactor comprising two interconnected polymerization
zones, a riser and a downcomer, as described in European Patent
EP782587. Hydrogen was used as molecular weight regulator. The
polymer particles exiting from the polymerization step were
subjected to a steam treatment to remove the unreacted monomers and
dried under a nitrogen flow.
[0138] The main precontact, prepolymerization and polymerization
conditions and the quantities of monomers and hydrogen fed to the
polymerization reactor are reported on Table 1.
[0139] The polymer particles were blended with 900 ppm of ADK-NA21
(Adeka Palmarole) in a Werner 53 extruder. Characterization data of
the so obtained composition are reported in Table 2.
Example 2C (Comparative)
[0140] Example 1 of WO 2008/012144.
TABLE-US-00001 TABLE 1 Polymerization conditions Example 1
Temperature (.degree. C.) 15 Residence time (min) 11 Catalyst (g/h)
2.0 Teal (g/h) 12.5 Teal/donor ratio (g/g) 3.5 Temperature
(.degree. C.) 30 Residence time (min) 6.5 Prepolymerization degree
(g pol./g 350 cat.) Temperature (.degree. C.) 70 Pressure (barg) 22
Residence time (min) 80 C.sub.2.sup.- /C.sub.2.sup.- +
C.sub.3.sup.- (mol/mol) RISER 0.055 H.sub.2/C.sub.3.sup.- (mol/mol)
RISER 0.013 C.sub.2.sup.- /C.sub.2.sup.- + C.sub.3.sup.- (mol/mol)
DOWNER 0.004 H.sub.2/C.sub.3.sup.- (mol/mol) DOWNER 0.0003 Notes:
C.sub.2.sup.- = ethylene; C.sub.3.sup.- = propylene; H.sub.2 =
hydrogen
TABLE-US-00002 TABLE 2 Composition characterization Example 1 2C
Ethylene content % 4.6 4.7 MFR "L" g/10' 2.0 2.0 Xylene solubles wt
% 14.2 12.8 T.sub.m .degree. C. 155.0 154.5 T.sub.c .degree. C.
118.2 116.3 Haze % 13.5 16.6 DB/TT .degree. C. -6.2 -5.4
[0141] The data in Table 2 confirm that the polyolefin compositions
of the present invention show improved optical (haze) properties.
Also their impact behavior (bi-axial impact resistance) is
improved.
* * * * *